Wiring a 1995 Chevy Astro for a Trailer

This is more of my continuing challenge of getting my 1995 Astro ready to pull a trailer to gaming conventions.

Apparently most Astros come with a factory towing option, some with a hitch receiver and factory wiring harness, some with just the wiring harness, and some not. Mine is one of the "nots". After discovering that there was no trailer wiring in the jack compartment of the Astro, I started opening up the interior to see if the factory had left me with the wires for the trailer hookup without installing the actual harness. Nothing. So my next step was tracing the wires back to a point where all of the necessary wires would be present.

Which turned out to be on the other side of the van behind the plastic panel that covers the same area that the jack compartment cover hides on the passenger side of the van. Three Torx head screws and a couple of snap fittings later, I had the panel off and could see the harness. The harness comes back through this area, goes up the driver side pillar, across the van to the other side and down the passenger side pillar.

I also had to remove both upper rear speakers in order to see the wiring harness, as well as the plastic cover that runs across the top of the back door area. With all of this out of my way, I was able to figure out which wires were which, in spite of the wiring not quite matching the wire diagram in my Haynes Manual.

After identifying the wires and making sure of where each one went, I marked the wires I need to tap into with blue masking tape marked with the letter of the wire color they go to on the trailer harness.

I bought a wire fitting to go into the 3/4" hole I drilled in the driver side compartment. A 1/2" hole may have worked better, but the 3/4" hole bit is the only drill bit I had on hand. Which is why I'm using adapters on the 1/2" fitting to make it fit the 3/4" hole. (oops...)

I also bought 12' of blue 12 gauge wire and 13' of orange 10 gauge wire for the two wires that lead to the front of the van. Blue for the brakes and orange for the 12v power line to the hitch. 12' of the blue because that's what was in the package at the auto parts store (FLAPS), and 13' of the orange because I had to go to Home Depot to get less than the 75' package that the FLAPS sold (the FLAPS didn't have orange anyway.) The extra foot was for insurance, in case I had misjudged the length needed for the project (hope the 12' of blue is enough...). I'm going to run those two in the channel where the wiring harness runs to the back of the van. Another good reason to put the connection to the trailer harness on the driver's side.

This is the jack compartment on the passenger side of the van. No trailer harness:

These are the only wires on the driver's side. There was black duct tape "insulating" the black wires under the wire wrap:

These are the wires on the Driver's side of the van. Now we're talking. The black drain line on the right goes to the storage compartment just over the wheel well. There's one on both sides of the van. I'm not sure why they would put drains on those two compartments, and not on the other two on the driver's side in the back:

These are the wires to the lights and to the driver side rear cargo door. I had to unwrap about two feet of wire in order to see which wire went where. This was mostly due to there being three yellow wires and two brown wires. Turns out that one of those three yellow wires is supposed to be white and goes to the third stop light on top of the van. I'm guessing that age changed the color of the wire to make it look yellow. More duct tape, too:

This is the driver side upper speaker removed to see the wires. For some reason, they ran the speaker wires up to the top speaker and then back down to the bottom speaker:

This is the "white" wire that runs to the third taillight:

This is a closeup of where I am going to tap into the wiring. The hole I drilled (after taking this picture) is next to the rubber one-way valve on the drain in the upper right hand corner of the picture. You can see how there is more than enough room to drill the hole:

This is the fitting that I'm going to use to run the harness through the floor and under the van. The black rubber seal is cut from a PCV valve grommet that I bought for sealing the hole around the trailer harness, before I purchased the fitting. The two "washers" are electrical bits used to size a hole down to a smaller size. I'll fill the fitting with some silicone to waterproof it:

Here are the two wires that I added for the power lead (orange) and the brake lead (blue). I also discovered that it takes 16' to reach the back of the van, not 12' or 13':

This is the piece of trim that I forgot to take a picture of while it was off. Under it is the channel for the wiring harness on it's way back to the rear of the van. Removing the driver side kick panel and this piece of trim will give you access to the wire path.

It gets interesting behind the driver's seat. The wire path goes around the seat belt pillar at its base and into the panel that runs along the side of the van. I removed all of the ashtrays and armrests in order to find access holes to help guide my home-made wire snake behind the panel. It took several hours of trial and error to get the snake all the way from the front, past the fuel filler hump and to the wheel hump. What a chore! (Next time, in the daytime. Not by flashlight again!)

As a side note, I believe that I found out why the two storage compartments on either side of the rear seat have drains. Examining one closely lead to the discovery that both are insulated with styrofoam and have insulated lids. The things are coolers! I would never have guessed this. Time to give them a really good cleaning just in case I should ever need to keep things cool in them:

Here is a close up of the wire connector installed with the wire. The connector was filled with high temp silicone (on the bottom side under the van) as I assembled it and tightened it down. The slight blueish tinge is from the locktite I used on the fitting:

Here is the connector as viewed from the under the van. The connector "points" towards the left rear corner of the van:

Here's a quick picture of the routing of the trailer wire from the socket to the connector. The connector is out of sight at the top of the picture:

Here is everything hooked up and ready for final taping and securing. I finally decided on grounding the harness to the mounting bracket for the rear compartments. It was my last choice, as I like to keep a ground as close to the frame as possible. But, I just could not find a spot that would allow me to use a bolt and nut instead of a self-tapping metal screw. After about an hour of stalling, I finally got out my multimeter and quadruple checked the ground dependability of that bracket before I drilled the hole and removed some paint for the bolt:

Here is everything taped, secured and ready for the panels to go back and be buttoned up. The 12 gauge blue wire and the 10 gauge black wire are the brake and power wires for the harness. I had enough wire to run them both forward to the point where the blue and orange wires from the front ended just slightly past the forward edge of the rear wheel well. Hence my remark above about needing 16' lengths of both wires to reach from the front to the back of the van. A side note, I usually do not like using those plastic wire taps, but in this case, it will help later if I've got the wires routed incorrectly. Which is also why I did not completely wrap the harness with tape. I may come back later and slip a sheet of plastic under the wire harness to protect it from any moisture that wicks under the cover through the carpet:

And here is a picture of the adapter in place that I bought assuming that my new trailer will have a 4-way flat connector. The LED's are test lights to verify the correct routing of the wires, and all three showed proper operation on my installation (the LED's work in conjunction with the lights. The top one blinks with the right turn signal, the middle one blinks with the left, and the bottom one comes on with the tail lights.) It works (Whoohoo!):

A hearty thank you to all who helped me with this project. Especially my son who braved the falling sand from the van frame, and the fire ants, to hold that connector in place as I tightened it from the inside.